John Glenn, who made history twice as the first American to orbit the Earth and the first senior citizen to venture into space, has died at the age of 95, the Ohio State University college bearing his name said Thursday.

The former astronaut had been admitted more than a week ago to the university's James Cancer Hospital, according to the John Glenn College of Public Affairs.

Wild giraffe numbers have plummeted by 40 percent in the last three decades, and the species is now "vulnerable" to extinction, a top conservation body said Thursday.

The population of the world's tallest land mammal dropped to below 100,000 in 2015, mainly due to habitat loss and illegal hunting, the International Union for the Conservation of Nature (IUCN) reported.

Dark matter, the mysterious substance believed to comprise a quarter of our Universe, is spread out more smoothly than previously thought, said a study Wednesday that may challenge some tenets of physics.

Authorities in Russia's Siberian region of Tuva on Monday were examining several pieces of the Progress cargo spaceship found after it crashed last week having failed to reach orbit.

Two pieces, including a large spherical object, were found by herders over the weekend, while another was discovered in the courtyard of a residential house on Monday, said the region's head Sholban Karaa-ool, warning people not to touch any metal debris.

Retired U.S. astronaut and the second man to walk on the moon, Buzz Aldrin, was recovering after his medical evacuation from Antarctica but is not yet able to return home, his manager Christina Korp said Sunday.

An unmanned cargo ship traveling to the International Space Station burned up in the atmosphere shortly after launching Thursday, the Russian space agency said, raising concerns over space travel safety.